In a microwave safe bowl, combine white chocolate and vegetable oil. Microwave in 30 second intervals, stirring in-between until completely melted and smooth.
Line a baking sheet with parchment paper or a silicone mat, then spread half the melted white chocolate onto the baking sheet. You’ll want the chocolate to be a rough 8x10 rectangle shape.
Transfer the baking sheet to the freezer for 10 minutes to let the chocolate harden.
In the meantime, cream together softened butter and granulated sugar. Add in milk and vanilla extract, then mix to combine.
Add the flour to a microwave safe bowl and microwave for 60-90 seconds to get rid of any wanted bacteria.
Sprinkle the heat-treated flour into the bowl of wet ingredients, then mix to form a dough.
Evenly press the edible sugar cookie dough onto the sheet of chilled white chocolate. Pour remaining white chocolate on top and spread into an even layer.
Immediately top with sprinkles, then return the baking sheet to the freezer for 10 minutes or until the bark is firm enough to break into pieces.